Thread cutting die head

ABSTRACT

A thread cutting die head incorporating a mechanism permitting the cutting tools (chasers) to be replaced quickly without demounting the head or major disassembly of the head and without disturbing the basic setting of the head.

United States Patent Youtz et al. [451 Oct. 10, 1972 [54] THREAD CUTTINGDIE HEAD [56] References Cited [72] Inventors: Donald E. Youtz; Edwin M.Eigen- UNITED STATES PATENTS bmdee both 1,639,712 8/1927 Strickland..408/148 [73] Assignee: Teledyne, Inc., Los Angeles, Calif. 2,082,7576/1937 Reimschissel ..408/ 148 l t l ..4 Filed: Sept. 1970 2,739,3223/1956 Reimschlsse e a 08/148 2 App]. 70 995 i Primary ExaminerCharlesW. Lanham Assistant Examiner-15. M. Combs Attorney-Strauch, Nolan,Neale, Nies & Kurz 52 .S. l. U C 10/95, 408/148, figs/[115538, ABSTRACT51 Im. Cl. ..B23g 1/00, B23g 5/10 A thread cutting die heedincorporating a mechanism [58] Field of Search ..10/95, 111, 120;408/148, 149, permitting the euning reels (ehasere) to be repleeedquickly without demounting the head or major disassembly of the head andwithout disturbing the basic setting of the head.

2 Claims, 5 Drawing Figures PATENTEDncI 10 4912; 3,596,454

SHEETIHFZ FIG! INVENTORS H 1 I 5 DONALD E. YOUTZ EDWIN M. EIGENBRODEATTORNEYS PATENTEDBBI w 1 2 3.e9s;454

SHEET 2 0F 2 FIG 3 INVENTORS DONALD E. Y, Z EDWIN MEI RODE wfi am /VATTO E5 THREAD CUTTING DIE HEAD BACKGROUND OF THE INVENTION The presentinvention is an improvement over the self-opening die head disclosed andclaimed in US. Pat. No. 2,739,322 granted Mar. 27, 1956 to applicantsassignee.

In a die head of this general type thread cutting chasers are mounted inchaser holders which are automatically moved radially of the headbetween open and closed positions. Usually four such chasers and chaserholders are employed in this type of head. The chaser holders aregenerally adapted for use in the threading of a small range ofworkpieces although the die head itself is capable of accommodating arelatively wide range of workpiece sizes. Accordingly, it is necessaryto replace the chaser holders as well as the chasers when the workpiecesize is changed sufficiently. Also, when the chasers become worn andrequire replacement, it is quite difficult to install new chasers andset them with the required precision and generally replacement of theworn chasers is effected by installing a replacement set of chaserholders with the new chasers in preset positron.

In a die head of the construction shown in the prior US. Pat. No.2,739,322 it is usually necessary to remove the entire die head from themachine in which it is installed and then disassemble the head to permitremoval and replacement of the chaser holders. Since the die head isusually a component of a larger machine or performs one machiningoperation in a series of automatically scheduled operations, the downtime of the entire machine occasioned by removal of the head is usuallyquite costly.

SUMMARY OF THE INVENTION It is the principal purpose and object of thepresent invention to provide improved thread cutting die heads whichfacilitate replacement of the chaser holders without requiring removalof the die head from the apparatus with which it is associated andwithout requiring special tools or techniques.

It is also an object of the present invention to provide improved dieheads incorporating means for effecting quick change of the chaserholders while retaining the structural rigidity and the desirableperformance characteristics afforded by prior die heads.

It is a further object of the present invention to provide improved dieheads incorporating means for quickly changing the chaser holderswithout substantially increasing the cost or complexity of the die head.

In die heads of this general type the chaser holders are moved alongradial guideways in the die head by a closing ring movable axially ofthe die head. In one limitof axial travel the closing ring holds thechaser holders in die-closed or operating position. In the other limitof axial travel, to which the closing ring is moved by relatively heavysprings; the closing ring holds the chaser holders in open position withthe chasers removed from the workpiece. The closing ring is held in eachlimit position by a latch mechanism and backup structure. To remove thechaser holders it has been necessary to remove the back-up structure andthe latch mechanism to permit the closing ring to move to a" third axialposition beyond its normal limits.

In accordance with the present invention a unique structure is providedwhich normally limits the movement of the closing ring between the usualopen and closed positions but, which, by manipulation of a singleexternally accessible part, selectivelypermits the displacement of theclosing ring to a third position which releases the chaser holders forremoval and replacement.

Additional objects and advantages will become apparent as thedescription proceeds.

THE DRAWINGS FIG. 1 is a central vertical section through a die headincorporating the present invention, showing the head in open position;

FIG. 2 is a fragmentary section taken along line 2-2 of FIG. 1;

FIG. 3 is a fragmentary elevation of the apparatus of FIG. 1 looking inthe direction of the arrows FIG. 3-3 of FIG. 1;

FIG. 4 is an end elevation partly in section of one component of the diehead shown separately; and

FIG. 5 is a transverse section taken along line 55 of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now more particularly tothe drawings, the die head includes a head body 20 having at one end ashank 22 adapted to fit the machine tool spindle in which the die headis mounted. At its opposite or forward end, thehead body 20 has anenlarged portion 24 provided with a plurality of dove-tailed slideways26 in which the chaser holders 28 are mounted for sliding movementradially of the head body. Tangential chasers 30 are adjustably securedin the holders 28 by conventional means.

The radial position of the chaser holders 28 is effected by a closingring 32 mounted for axial sliding movement on the head body. At itsforward end the closing ring 32 is provided with forwardly projectingprongs 34, one for each of the four chaser holders, which extend throughopenings 36 into slideways 26. As more fully explained in US. Pat. No.2,739,322, the prongs 34 of the closing ring and the chaser holders 28are formed with inclined cam guideways 38 which are so arranged thataxial movement of the closing ring produces radial movement of thechaser holders for moving the chaser holders into or out of threadcutting position or for adjusting the cutting position to various workdiameters within the range of the chaser holders.

FIG. 1 illustrates the position of the parts when the die head is open,a position to which the closing ring is constantly urged by a pluralityof springs 40 compressed between the forward portion of the die headbody and the adjacent portion of the closing ring 32. The limit positionof the closing ring is determined by a pair of abutments 42 formed onlatch ring 44, the abutments engaging the bottom of an annular groove 46in the rear face of the closing ring 32.

The die head is opened and closed by an operating ring 48 having aperipheral groove 50 for engagement by the usual yoke, not shown, forshifting the operating ring axially between thereiriicted position shownand an advanced position to displace the closing ring to the left asviewed in FIG. I to the dotted line position A,

which is the die-closed position. As more fully explained in US. Pat.No. 2,739,322 when the closing ring 32 has been displaced forwardly, orto the left as viewed in FIG. 1, the latch ring 44 is displaced radiallyby a spring 52 to dispose abutments 42 opposite rear surface portions 54and 56 of the closing ring to hold the latter in die-closed position.

The die head is subsequently opened by retraction of the operating ring48 to cause a bevelled surface 58 to contact a similarly bevelledsurface 60 on the latch ring 44, to displace the latter radially to theposition shown in FIG. 1, thus permitting the springs 40 to retract theclosing ring 32 to the position shown in FIG. 1.

The structure thus far described may be identical with that disclosedand the aforesaid US. Pat. No. 2,739,322 to which reference may be hadfor further details of construction.

In accordance with the present invention the axial position of the latchring 44 and the closing ring 32 is determined by a latch thrust ring 62mounted for limited rotary movement and for limited axial slidingmovement on the sleeve portion 64 of an adjusting ring 66 adjustablythreaded on the shank portion 22 of the head body 20.

The forward face of the thrust ring 62 has a radial groove 68 for thereception of the corresponding portion of the latch ring 44, the latchring being thus permitted to move laterally between its two operatingpositions. The thrust ring 62 is positioned on the adjusting ring 66 bythree radial pins 70 press-fitted into the thrust ring and extendingradially inward into cam slots 72 formed in the adjusting ring. As bestshown in FIG. 3, one end of the cam slot 72 is provided with detentportion 74 in which the pins 70 are received when the thrust ring 62 isin operating position. The thrust ring is also securely locked in thisposition by a latch 76, pivoted as at 78, on the thrust ring and havinga tongue 80 adapted to fit in a slot 82 in the sleeve portion of theadjusting ring. The latch is held in locked position by a springassembly 84 suitably mounted in the thrust ring. Suitable wrenchreceiving sockets 86 are provided on the thrust ring to facilitatemovement of the ring when required.

The adjusting ring 66 is threaded on to the shank 22 of the die headbody and is split as at 88, to permit the ring to be selectively clampedin adjusted position by a clamp bolt 90.

When it is desired to replace the chaser holders 28 a suitable tool isinserted in the sockets 86 and the thrust ring 62 is rotated to move thepins 70 out of the detent portion 74 of the cam slot 72, and then topermit the pins 70 to travel to the opposite end of the cam slot underthe influence of the opening springs 40. The opening springs 40 willurge the closing ring 32 to dotted line position B carrying with it thelatch ring 44 and the operating ring 48. When the closing ring 32reaches its limit position the chaser holders 28 may be freely withdrawnradially of the die head.

The alternate set of chaser holders with the chasers pre-positionedtherein are then fitted into the guide ways 26. To assure proper radialpositioning of the chaser holders for subsequent engagement with thetongue and groove of the closing ring 32 a detent assembly 92 isprovided in the head portion 24 for engagement with a recess 94 in thechaser holder 28. This construction eliminates the annoying and timeconsuming task of manually properly pre-positioning the four chaserholders simultaneously which is extremely difficult since the axis ofthe die head is normally horizontal.

After the new chaser holders have been positioned, the thrust ring isagain rotated, and, as the pins travel along the cam slot 72, thesprings 40 are compressed. When the pins 70 have been returned to thedetent portion 74 in the cam slot, the apparatus is ready for operation.Any necessary adjustments may be made by loosening the clamp bolt 90,rotating the adjusting ring 66 as required, and tightening the clampbolt.

From the foregoing it will be apparent that the present inventionfacilitates the changing of chaser holders in minimum time withoutrequiring disassembly of the unit or removal of the unit from themachine with which is associated. Further, the manual manipulation ofthe parts has been simplified so that the changing operation can beperformed even where the die head is relatively inaccessable or wherethe space around it is severely limited.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:

1. In a die head in which chaser holders are moved radially on a bodymember by a control member movable axially of the body member betweentwo limit positions, said chasers being released from said body memberupon movement of said control member beyond one limit position to arelease position, an adjustment member mounted on said body, saidadjustment member having an external support surface, an annular thrustmember mounted on said support surface for limited axial and rotarymovement thereon, said thrust member being effective to limit movementof said control member, and cooperating cam and cam follower means onsaid adjustment member and said thrust member for effecting selectivemovement of said thrust member between a first position for preventingmovement of said control member beyond said one limit position, and asecond position permitting movement of said control member to saidrelease position.

2. The die head according to claim 1, together with a latch mechanismfor releasably locking said thrust member against movement on saidadjustable member when said thrust member occupies said first position.

1. In a die head in which chaser holders are moved radially on a bodymember by a control member movable axially of the body member betweentwo limit positions, said chasers being released from said body memberupon movement of said control member beyond one limit position to arelease position, an adjustment member mounted on said body, saidadjustment member having an external support surface, an annular thrustmember mounted on said support surface for limited axial and rotarymovement thereon, said thrust member being effective to limit movementof said control member, and cooperating cam and cam follower means onsaid adjustment member and said thrust member for effecting selectivemovement of said thrust member between a first position for preventingmovement of said control member beyond said one limit position, and asecond position permitting movement of said control member to saidrelease position.
 2. The die head according to claim 1, together with alatch mechanism for releasably locking said thrust member againstmovement on said adjustable member when said thrust member occupies saidfirst position.